<template>
  <div class="child">
    <h3>我是Child组件</h3>
    {{ sum }}
  </div>
</template>

<script>

import {ref} from 'vue'
export default {
    name:'MyChild',
    async setup(){
        let sum  =  ref(0)
        let  p  =new Promise((resolve,reject)=>{
         setTimeout(()=>{
            resolve(sum)
         },3000)
        })
        return await p
    }

}
</script>

<style>
	.child{
		background-color: skyblue;
		padding: 10px;
	}
</style>